Im hoping this will be a sticky, so im going to ask for permission.
To properly care for you betta, you need to learn how to tell male and female apart to know their own needs. Or you could just end up with a bunch of dead males in a tank (thinking they were females). No one wants that do they? (HOPEFULLY THAT'S A {NO}) LOL.
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Well it is really easy actually. The females have a white dot and males dont. The white dot or "egg spot" is sometimes hard to find. You just have to look carefully.

Also (Most of the time) the females have shorter fins. This is not always correct because there have been females with long fins and somtimes there have been females that looked better than the males.

So it is a myth that females are less "flashy" and colorful than the males.

For example here is a female with fairly large fins:

In this picture you cant really see the Ovipositor spot but in the video when the fish goes up you can see the egg spot.

Very nice, however, sometimes a male will have an egg spot or ovipositor and some females may not show it well and not always a good indicator of sex....I have found fins and body-shape/size to help me determine sex more than just the ovipositor alone.....

Very nice, however, sometimes a male will have an egg spot or ovipositor and some females may not show it well and not always a good indicator of sex....I have found fins and body-shape/size to help me determine sex more than just the ovipositor alone.....